System and method for robust treatment planning in radiation therapy

Abstract

Robust optimization systems and methods are provided for intensity modulated proton therapy (IMPT) that may be deployed in a clinically practical way to enable users to control the balance between nominal plan quality and plan robustness in a user-defined way. The method may include a normalized dose interval volume histogram (NDIVH)-based robust optimization, where the normalized dose interval (NDI) is calculated for each voxel considering dose variations in the face of uncertainties. It is then used to create a NDIVH. The area under this NDIVH curve may then be used to quantify plan robustness. By using normalized dose interval volume constraints (NDIVC) to control the shape of the NDIVH curves, plan robustness may be adjusted. The tradeoff between nominal plan quality and plan robustness can be modified in a user-defined way by adjusting positions of the NDIVCs on the NDIVH curves.

The invention claimed is: 
     
       1. A method for balancing radiation therapy plan robustness and nominal plan quality, comprising:
 a) determining constraints for a radiotherapy plan quality; 
 b) calculating normalized dose interval for a plurality of voxels in at least one normal tissue region of interest (ROI) and at least one target ROI in a subject; 
 c) generating a normalized dose interval volume histogram using the normalized dose interval for the plurality of voxels in the at least one normal tissue ROI and the at least one target ROI in the subject; 
 d) measuring an area under the normalized dose volume histogram to determine the robustness for the plan; and 
 e) generating the radiotherapy plan using the normalized dose interval volume histogram (NDIVH) through the use of the normalized dose interval volume constraints. 
 
     
     
       2. The method of  claim 1 , wherein the normalized dose interval are used to control the shape of the dose interval volume histogram. 
     
     
       3. The method of  claim 1 , wherein the normalized dose intervals (NDI) are determined by: NDI=(D max −D min )/D max ,
 where D max  represents the maximum dose, and D min  represents the minimum dose among possible doses corresponding to different setup and range uncertainty scenarios for the plurality of voxels in the at least one normal tissue ROI and the at least one target ROI in the subject. 
 
     
     
       4. The method of  claim 3 , wherein the NDI are a 3D distribution in the subject. 
     
     
       5. The method of  claim 1 , further comprising minimizing an objective function that incorporates the plan quality and the plan robustness to generate the radiotherapy plan. 
     
     
       6. The method of  claim 1 , further comprising optimizing an objective function that incorporates the plan quality and the plan robustness to generate the radiotherapy plan using the normalized dose interval. 
     
     
       7. The method of  claim 1 , wherein creating the radiotherapy plan includes adjusting a position of the normalized dose interval in the normalized dose interval volume histogram to balance between nominal plan quality and plan robustness. 
     
     
       8. The method of  claim 1 , wherein the constraints include at least one of a threshold for plan robustness, a threshold for plan quality including target dose coverage, target dose homogeneity, normal tissue protection value, patient setup uncertainty value, proton beam range uncertainty value, or a combination thereof. 
     
     
       9. The method of  claim 1 , further comprising generating a dose volume histogram prior to generating a normalized dose interval volume histogram. 
     
     
       10. A system for balancing radiation therapy plan robustness and nominal plan quality, comprising:
 a computer system configured to:
 i) determine constraints for a radiotherapy plan quality; 
 ii) calculate normalized dose interval for a plurality of voxels in at least one normal tissue region of interest (ROI) and at least one target ROI in a subject; 
 iii) generate a normalized dose interval volume histogram using the normalized dose interval for the plurality of voxels in the at least one normal tissue ROI and the at least one target ROI in the subject; 
 iv) measure an area under the normalized dose volume histogram to determine the robustness for the plan; and 
 v) generate the radiotherapy plan using the normalized dose interval volume histogram (NDIVH) through the use of the normalized dose interval volume constraints. 
 
 
     
     
       11. The system of  claim 10 , wherein the normalized dose interval are used to control the shape of the dose interval volume histogram. 
     
     
       12. The system of  claim 10 , wherein the normalized dose intervals (NDI) are determined by: NDI=(D max −D min )/D max ,
 where D max  represents the maximum dose, and D min  represents the minimum dose among possible doses corresponding to different setup and range uncertainty scenarios for the plurality of voxels in the at least one normal tissue ROI and the at least one target ROI in the subject. 
 
     
     
       13. The system of  claim 12 , wherein the NDI are a 3D distribution in the subject. 
     
     
       14. The system of  claim 10 , wherein the computer system is further configured to minimize an objective function that incorporates the plan quality and the plan robustness to generate the radiotherapy plan. 
     
     
       15. The system of  claim 10  wherein the computer system is further configured to optimize an objective function that incorporates the plan quality and the plan robustness to generate the radiotherapy plan using the normalized dose interval. 
     
     
       16. The system of  claim 10 , wherein creating the radiotherapy plan includes adjusting a position of the normalized dose interval in the normalized dose interval volume histogram to balance between nominal plan quality and plan robustness. 
     
     
       17. The system of  claim 10 , wherein the constraints include at least one of a threshold for plan robustness, a threshold for plan quality including target dose coverage, target dose homogeneity, normal tissue protection value, patient setup uncertainty value, proton beam range uncertainty value, or a combination thereof. 
     
     
       18. The system of  claim 10 , further comprising generating a dose volume histogram prior to generating a normalized dose interval volume histogram.